Changing your way of thinking is not evolution.
The evolution was the actual upgrades.
Not evolved, but re-written. They were "uplifted" just like the Salarians "uplifted" the Krogan before they were ready. They were given advancements before their time. They didn't evolve into their being through trial and error. They weren't given the time and failures necessary to achieve appreciation for their new found power.
Why are you worshiping this natural selection thing? It's not objectively better. Every single race in the galaxy found technology beyond them and used it to advance to make it to the stars. The krogan were a problem only because of their culture and how they were used; it had nothing to do with the tech itself.
The "uplifted" Geth would have been no better for the galaxy than the "uplifted" Krogan. The Salarians were wrong to use the Krogan as a weapon against the Rachni before they were ready. The result was that they had to be put back down with the Genophage. Tragedy begets tragedy.
This is incredibly silly. The geth, at least if you rewrite them in ME2, are one of the strongest forces against the Reapers.
Synthesis is another "uplifting" of the entire galaxy. Trying to skip the long process of learning from failures and just go straight to undeserved power. Power without the appreciation (and sometimes horror) of its creation inevitably leads to abuse.
You can get abuse anywhere, but Synthesis is the culmination of previous unity, not its repudiation. Synthesis is a reward, a means of using said unity to go on to ever-greater heights.